This invention relates to fault diagnosis devices for diagnosing causes of faults of various devices and apparatus such as industrial machines or of systems of such devices, etc.
A conventional fault diagnosis device is disclosed, for example, in R. Cantone, "Diagnostic Reasoning With IN-ATE.TM.", Proceedings of A. I. '87 Conference, April, 1987. The diagnosis by means of such fault diagnosis device is effected in accordance with the binary search tree of FIG. 5. Thus, first a test t7 16 at the root node of the fault tree is effected, and the result of true (t) or false (f) is obtained. When the result is false (f), a test t1 17 is effected. If the result at the test t1 17 is false (f), a UUT (unit under test) input fault 18 is inferred. If the result at the test t1 17 is true (t), the test t3 19 is performed, to continue the diagnosis.
The above conventional fault diagnosis device effects diagnosis via a binary fault tree. Thus, it has the following two disadvantages.
First, it is incapable of performing two or more test simultaneously and comparing the obtained observation data so as to determine one cause from among three or more causes of fault or from an intermediate hypothesis on causes of fault.
Second, in the case where the devices under test are complicated, the binary fault tree therefor becomes large and complicated. Thus, the preparation of the fault tree becomes difficult. Further, when the whole fault tree cannot be loaded into the main memory of the computer, the execution of the diagnosis becomes extremely slow or even infeasible.